CANON ES-71II Lens Hood for EF 50mm f/1.4 USM 

Acts as a shade (visor) and prevents stray light from entering your lens, thus reducing glare and flare for better visibility and image quality. It also helps to protect your lens, as it adds an extra layer of protection to your front lens element. A must have when your subject is backlit, you’re shooting into or near strong sources of light (like the sun), you’re using off-camera flash that creates lens flare, or when you’re shooting near street lamps, cars with their lights on, buildings etc.

Generic Lens Hood